Monday, August 5, 2013

Mapping Roatan's spectacular deep reefs

>>> geolocalization with the Marine GeoGarage <<<
Credit: Scott Harris, College of Charleston

From Schmidt Ocean

The Falkor team has just completed the first-ever high-resolution map of deep reefs near the island of Roatan in Honduras.
This new resource will not only aid future research in the area on the corals and other animals found there, it could also enable increased conservation of the reefs.

When Dr. Peter Etnoyer, a marine ecologist at NOAA’s National Centers for Coastal Ocean Science, realized a few months ago that R/V Falkor would be headed for the Panama Canal after the Oases 2013 project, he saw a unique opportunity looming.

Since 2010, Etnoyer and his colleagues, with support from Schmidt Ocean Institute, have been exploring small portions of the deeper slopes on the Meso-American Barrier Reef off Roatan’s coast. They’ve worked from the Idabel submersible that Karl Stanley built himself.

Raw mapping data from a pass with Falkor's sonar.
Credit: Schmidt Ocean Institute

But that research was almost hit-or-miss at times because existing maps for these reefs were of such low resolution.
Like many remote regions, the best available seafloor maps come from satellite data and have a resolution of at best 1km—that means you can’t even discern the rocky plateaus and outcroppings where corals are found, which are typically much smaller than a kilometer.
But, Falkor’s sonar system creates maps with resolution in the 5 to 10-meter range, which reveals those critical features.

After realizing how close Falkor would be to Roatan on it’s trip to the Pacific, Etnoyer and Matt Rittinghouse, a graduate student at the College of Charleston whom Etnoyer is advising, put together a quick proposal requesting that the team divert there to map a huge swath of the barrier reef’s deeper reaches.
The project was quickly approved as a perfect fit for Schmidt Ocean’s mission to generate new ocean knowledge and make it publicly available.

 A garden of crinoids on a deep Roatan reef.
Credit: Peter Etnoyer/Karl Stanley

By the end of the day on July 10th, the ship’s crew had mapped a few hundred square kilometers of the continental slope in depths mainly from 300 to 1,000 meters, but as deep as 2,500 meters.
The total area covered is in the range of 300 square kilometers.

The maps will allow researchers to target the most interesting portions of the reefs for future explorations.
By the end of the year Etnoyer’s team hopes to use the new map to identify and then explore new ridges and gullies no one even knew existed.
And, if all goes well, the Ocean Exploration Trust, founded by Robert Ballard, also plan to use their impressive Hercules ROV to explore portions of these deep reefs as well, which would offer much more sample collection than possible with Idabel.

 A deep scene on the Meso-American Barrier Reef with brittle stars intertwined with sea fans.
Credit: Peter Etnoyer/Karl Stanley

The maps should also be a major step forward for deep reef conservation.
Right now, a large chunk of Roatan’s portion of the barrier reef is set aside as the Sandy Bay West-End Marine Reserve, but that was designed to protect shallow corals and does not extend very far out to sea.
That means the area’s spectacular deep reefs, which support countless fish and corals, are open to fishing.

Etnoyer and Rittinghouse will combine the results of past research on where deep corals are found, and data from past Idabel video surveys, with the new mapping data to delineate key deep-sea coral habitats.
Once this knowledge is available, local organizations, which strongly supported the permit application for the Falkor work, plan to push to extend the bounds of the protected areas so that the lesser-known but critically important deep reefs can also be protected.
“Our role here is to provide as much useful information as we can to the local groups to help them make their own management decisions,” says Etnoyer.

Raw data from the mapping will become available shortly at NOAA’s National Geophysical Data Center site.
Over the next several months the researchers will be processing the data into maps that they’ll distribute to Roatan groups and officials, and add to Google Earth.

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